[RE-wrenches] DC Series Fusing in inverters

[Kirpal Khalsa]

Jason...as you know, the fusing should match the max series fuse ratings of
the module requirements per the module manufacturer....If strings are
individually fused and combined before the fused disconnect box then the
fuses often need to be changed from the factory supplied 15A fuses....Note
the maximum allowed by SMA per the disconnect limitations per string of
their disconnect.....Fronius used to supply metal slugs that fit in the
fuse holders if no fusing was required on the input.....
Didn't some of the Evergreen modules call for 20A series fuses?
Good luck..

Sunny Regards,
Kirpal Khalsa
NABCEP Certified PV Installation Professional
Renewable Energy Systems
www.oregonsolarworks.com
541-218-0201 m
541-299-0402 o


On Thu, Feb 6, 2014 at 9:56 AM, Glenn Burt <glenn.burt at glbcc.com> wrote:

> I think I just read that SMA has changed their long-standing 15A per
> string fuses to 20A.
>
> You might look to see if it applies to existing systems.
>
> Hope it helps.
>
>
>
> Glenn
>
>
>
> *From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
> re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *Jason Szumlanski
> *Sent:* Thursday, February 06, 2014 12:50 PM
> *To:* RE-wrenches
> *Subject:* [RE-wrenches] DC Series Fusing in inverters
>
>
>
> SMA inverters typically come with 15A KLKD fuses pre-installed. I have
> seen a bunch of blown fuses recently (after cold weather)... It seems that
> some dealers are just assuming the 15A fuse is okay for series strings and
> not doing the calculations. I've been finding quite a few Evergreen systems
> or parallel connected two-string SunPower systems that should have 20A
> fuses per NEC 690.8. The problem does seem to be worse where inverters are
> exposed to direct sunlight, presumably from fuses that no longer meet their
> ampacity rating due to heat.
>
>
>
> Anyone else run into this frequently?
>
>
>
> Jason Szumlanski
>
> Fafco Solar
>
>
>
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